In 1971 -born Oliver Waespi is now one of the most prolific composers of Switzerland . With the mother - daughter duo Praxedis ( Praxedis Hug - Rütti , harp , and Praxedis Geneviève Hug, piano ) and a symphonic bands Instrumentation composed Double Concerto he faced a challenging task whose difficulty naturally exist in the field of sound balance . Waespi uses the solo instruments in the outer movements as quasi percussive addition to what is happening in the orchestra , as he acknowledges them in the middle movement "Air" wide space for sparse and contrasting accompanied cadenzas . A great , new composition inspired in a avancierten style of felt 20 minutes , but actually a good half hour